Many imaging devices, such as printers, facsimile devices, multifunction peripherals (MFPs), etc., dispose images onto a print media, such as paper, using a fluid-ejection device, such as an inkjet print head, that ejects droplets of a marking fluid, such as ink, onto the print media through a set of nozzles. One problem is that the nozzles, especially seldom used nozzles, frequently become clogged or otherwise contaminated with a variety of contaminants, such as dried ink and paper fibers. This adversely impacts the placement and volume of output droplets, as the droplet may be deflected from its intended destination and less than all ink may escape the nozzle. Conventional imaging devices often include a spittoon in which ink drops are periodically disposed (or “spit”) to purge the nozzles.
Some imaging devices employ a separate fluid-ejection device that ejects droplets of a clear fixing liquid (or “fixer”) onto the print media prior to depositing the ink (often referred to as “under-printing”), e.g., to improve color saturation, water-fastness, edge acuity, and durability of inkjet printed images, etc. This is achieved when the fixing liquid reacts with the inkjet ink either on or in the print media. A clear fixing liquid can also be overprinted onto inkjet printed images, e.g., to reduce drying time and smearing, increase image permanence, etc.
Typically, the fluid-ejection device is expected to deposit the clear fixing liquid in a precise pattern corresponding to the printed images. One problem is that fixing liquids can crust nozzles on the fluid-ejection device, internally and externally, and thus degrade nozzle performance, more quickly than ink. Such nozzle degradation can produce an inferior image with inferior image uniformity and permanence. Consequently, fixing liquids have to be purged (or spit) more frequently and in larger quantities than inks, causing spittoons to fill more quickly, leading to increased spittoon maintenance. Moreover, fixing liquids often react with the ink contained in a spittoon, e.g., causing the inks to solidify within the spittoon, leading to spittoon malfunction.